Carbon bisulfide production



July 12, 1955 K. w. GUEBERT n CARBON BISULFIDE PRODUCTION Filed May 28, 1951 United States Patent l(iM-lice 2,712,982 Patented July l2, 1955 CARBON BISULFIDE PRODUCTION Kenneth W. Guebert, Freeport, Tex., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Application May 28, 1951, Serial No. 228,731

5 Claims. (Cl. 23-206) This invention relates to carbon bisulde production, and, more particularly, to a novel catalytic process for the manufacture thereof from sulfur and a'parainic hydrocarbon.

lt was known prior to the present invention that parafnic hydrocarbons and sulfur, in liquid phase or in vapor phase, would react at elevated temperatures to produce carbon bisulfide and hydrogen suliide. lt was also known that this reaction was catalyzed by certain agents, such as silica gel, fullers earth, bauxite, activated alumina,

copper phosphate, zirconium phosphate, and thorium f phosphate.

The present invention is based upon the discovery of a novel catalytic agent for the reaction between sulfur and a parafinic hydrocarbon.

According to the invention carbon bisullide is produced by contacting, at a temperature from 500 to 700 C., a vapor phase mixture of sulfur and a paratiinic hydrocarbon with magnesium oxide promoted by at least one oxide of nickel, cobalt, or molybdenum.

Magnesium oxide catalysts promoted with a nickel oxide, a cobalt oxide, or a molybdenum oxide are readily produced by irnpregnating particles of MgO of suitable size with an aqueous solution of nickelous chloride, cobaltous chloride, or molybdenum tetraor penta-chloride,

drying the impregnated particles, and heating them in an air stream at from 400 to 600 C. It is usually preferred that the magnesium oxide be promoted with from l to l0 per cent of one or more of the other named oxides. The terms per cent and parts are used herein to refer to per cent and parts by weight, unless otherwise indicated.

The process of the invention may be more readily understood by reference to the accompanying drawing, which is a schematic ow sheet illustrating the production of carbon bisulide, using a promoted magnesium oxide catalyst.

Liquid sulfur from a supply 11 llows through a line 12 and into a line 13 where it is mixed with natural gas from a supply 14 which ows through a line 15 into the line 13. The natural gas-sulfur mixture passes through the line 13 into a vaporizer 16 and from thence through a line 17 to a reactor 18 packed with the promoted magnesium oxide catalyst. Reaction products pass from the reactor through a line 19 to a condenser 20 Where any unreacted sulfur is removed. Products remaining pass from the sulfur condenser through a line 21 to a cooled trap 22 where carbon bisulde and some hydrogen sulfide are condensed and collected. The remaining products, mainly HzS, then ow through a line 23 to a scrubber 24 where hydrogen sulfide is absorbed by dilute aqueous sodium hydroxide passed into the scrubber through a line 25. Relatively dilute sodium sulfide passes from the bottom of the scrubber through a line 26. Any remaining gas leaves the system through a vent 27.

The method of the invention is suitable for the production of carbon bisullide at temperatures ranging from 500 to 700 C. However, it is preferred to carry out the invention.

`factorily at atmospheric pressure, although either re duced or elevated pressures can be used if desired.

It is practical to carry out the process of Vthe invention using a space velocity from 200 to 1200. Space velocity is defined as the ratio of -total volume of the gases, calculated at 0 C. and 760 mm. Hg total pressure, passed over the catalyst per hour divided by the apparent volume of the catalyst. Within the above range, vthe selectionof `a lower space velocity results in a higher yield, but a lower production rate per unit of reactor volume. Accordingly, the space velocity used in a given application is a compromise between these two factors. It is usually preferred that the space velocity be from 700 to 900.

In general, any available source of parainic hydrocarbon gases can be used in carrying out the process of Natural gas provides a convenient supply, preferably a natural gas high in methane. Although it is feasible to carry out the reaction of the invention using a substantial excess either of sulfur or of the parar'iinic hydrocarbon, it is usually preferred to use from 90 to 110 per cent of the sulfur theoretically required to convert all the carbon in the parainic hydrocarbon to carbon bisulde, and all the hydrogen therein to hydrogen sulfide.

EXAMPLE Carbon bisuliide was produced at a space velocity of 890 from a Texas natural gas containing about 90 per cent by volume of methane by passing a vapor mixture of sulfur and the natural gas, in a ratio of about l5 parts of the latter per 100 parts of the,former, over particles of magnesium oxide of from 8 to 14 mesh U. S. Sieve Series promoted by nickelous oxide. The promoted magnesium oxide was produced by impregnating particles thereof of the indicated size with an aqueous solution of NiClz, drying the impregnated particles, and heating them in a stream of air, as described above. The per cent conversion of natural gas charged to carbon bisulde was found to be a function of temperature, ranging from a 44 per cent conversion at a reaction temperature of 530 C., to a 60 per cent conversion at a reaction temperature of 566 C., 64 percent conversion at a reaction temperature of 574 C., and 80 per cent conversion at a reaction temperature of 620 C.

The procedure of the preceding paragraph was repeated using magnesium oxide promoted by an equimolecular mixture of CoO and M003, and magnesium oxide promoted by CoO. The results achieved at different temperatures using these two catalysts are presented in the table below:

Table Reaction Percent Identicatlon N o. Promoter Temp., Conversion C. to CS2 MOOa-COO 547 20 Moos-C00 570 40 MoOa-CoO 580 48 Moos-C00 601 61 MoOs-CoO 620 69 C00 588 43 C00 620 89 C00 640 82 l. A method of producing carbon bisuliide that comprises contacting a vapor phase mixture of sulfur and a parainic hydrocarbon with a catalyst composed of magnesium oxide promoted by from 1 to 10 percent of an oxide of a metal of the group consisting of nickel, molybdenum and cobalt at a temperature from 500 to 700 C.

2. A method as claimed Vin claim 1 in which the tem- 2,187,393 De Simo Ian. 16, 1940 perature is from Y560 to600 C.V 2,322,555 Winding June 22, 1943 3. A method as claimed in claim 2 in which the mag- 2,330,934 Thacker Oct; 5, 1943 nesium oxide is promoted by a nickel oxide. 2,369,377 Thacker Feb. 13, 1945 4. A method of producing carbonY bisulde that com- 5 2,428,727 Thacker Oct. 7, 1947 prises contacting a vapor phase.V mixture of sulfur and 2,565,215 Folkns etal. Aug. 21, 1951 methane with a catalyst consisting of kmagnesium oxide 2,616,793 Folkins et al. Nov. 4, 1952 promoted by from 1 to 10 per cent of a nickel oxide at 2,636,810 Marisic Apr. 28, 1953 atemperature from 560 to 600 C. OTHER REFERENCES,

5. A method as claimedin claim 4 in which the space 10 yelocity is from 200 to 1200. Kalichevsky: Chemical Rening of Petroleum, 1933,

. A pages 173-178. References Cited in the file of this patent UNITED STATES PATENTS ,2,079,543 Bley May4, 1937 15 

1. A METHOD PRODUCING CARBON BISULFIDE THAT COMPRISES CONTACTING A VAPOR PHASE MIXTURE OF SULFUR AND A PARAFFINIC HYDROCARBON WITH A CATALYST COMPOSED OF MAGNESIUM OXIDE PROMOTED BY FROM 1 TO 10 PERCENT OF AN OXIDE OF A METAL OF THE GROUPS CONSISTING OF NICKEL, MOLYBDENUM AND COMBALT AT A TEMPERATURE FROM 500* TO 700* C. 